1. Field of the Invention
This invention relates to the field of digital communications, and more specifically to a digital bridging apparatus having particular utility in telephone conferencing systems.
2. Description of the Prior Art
Telephone conferencing, the connecting of three or more telephones simultaneously into a single circuit, has existed for many years. Most such systems utilize analog signals, and the output of the switching circuit is merely the algebraic sum of the inputs. This technique is not possible with digital voice communications networks because there is no known technique for summing the individual binary signals and subsequently decoding the sum back into an intelligible analog voice signal.
For many reasons, including a need for increased data transmission rate capability and for maintaining overall transmission quality, it is highly desirable to provide conferencing capability to digital telephone networks. Such capability has been provided in the past either by networks which allow for only one conference call to occur at a time or by networks which require a separate digital bridge for each allowable conference call. The disadvantages of the prior art are obvious: the first has severely limited capability and the second is highly complex and expensive.